My DAC can only output voltages between 0-5 V and I want to linearly shift the range to -2.5 to 2.5 V. For example, a 2.5 input would (ideally) lead to a zero volt output. Likewise, a 5 V input would lead to a 2.5 V output. What circuit would be ideal for this? Thanks in advance!
Electronic – Omp Amp Design for shifting a voltage range
dacoperational-amplifier
Related Solutions
In normal operation, V+ and V- are the same. If they are different, the op-amp is being used as a comparator.
An important spec in choosing an op-amp is the "input common-mode voltage" range. The voltages at the inputs must be in this range for proper operation.
Some op-amps are "RRIO" or rail-to-rail input/output. As you might guess, this means the input common mode range goes from the Vee rail to the Vcc rail.
Some op-amps which include only the Vee rail in the common-mode range are referred to as "single-supply" op-amps.
Here is the spec in the LM324 datasheet:
Your approach isn't a great idea for this application. You almost never see it that way in instrumentation design.
What you want to do is implement a series of sensing scales. That is you have a system that can work over different light intensity ranges and you switch between them to effectively increase your dynamic range (range of light input you can handle) without increasing your voltage range. As a bonus you can get higher sensitivity from the decreased power supply noise (greater CMRR) if you're careful.
Here is an architecture that I helped develop:
The module looked like this:
It could go from complete darkness to well beyond 10k lux with accuracy better than the commercial meters of its day on a single 5V rail. You can find a number of papers by me and others on the project here.
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Best Answer
The simplest way is to reverse your 0V-5V to 5V-0V in firmware and use a subtracting circuit:
simulate this circuit – Schematic created using CircuitLab
Optionally, add another inverting amplifier afterward to get -2.5V to +2.5V for 0-5V in.
The reference and resistor accuracy, and op-amp type will depend on your required precision. The op-amps will require a dual supply such as +/-5V, of course.